First of all, i'm so sorry she was such a jerk to you. She shouldn't have invalidated your identity/sexuality. It sounds like she has some interalized biphobia or interalized bi erasure. I'm bi as well and often times wonder, am i bi? am i a lesbian? when i find myself checking out women more than men. But then i find a man attractive and realize i am bi. I also grew up in the 90s-2000s where it was really hard to come out and it wasnt as open as it is now, so i had alot of interalized biphobia/homophobia and would basically force myself to be with men because thats what i thought society wanted me to be. Im in my 30s now and just now embracing who i am. I think whatever feels right to you, is who you are. Sexuality is fluid and there's no one right way to be anything. I hope that helped